Ultrastructure of normal, metaplastic, and abnormal human uterine cervix: use of montages to study the topographical relationship of epithelial cells.

The ultrastructure of the entire thicknesses of normal and abnormal human uterine cervical epithelia is studied with the use of slit-type grids. In four normal squamous epithelial specimens, basic similarities in the maturational sequence were apparent; however, significant variation in the progression of differentiation was also obvious. Because of this variation, it was not possible to always correlate cellular structure with cellular location within the epithelial strata. Four normal specimens containing combinations of squamous, columnar, and metaplastic cells show variations in the topographical relationships of these cells and stages in the transition of reserve to squamous cells in metaplastic zones. The presence of cells with features characteristic of squamous and columnar epithelia suggests a bipotentiality of reserve cells. Six abnormal specimens share several morphologic features, which usually, but not regularly, vary quantitatively with the extent of abnormality. Because of the inconsistent gradation of cellular features with lesion severity, it was essential that numerous ultrastructural parameters be considered in order to evaluate the extent of abnormality. Cellular features peculiar to individual specimens include edema, keratinization, phagocytic squamous cells, and cells similar in appearance to koilocytes described in condylomas. Electron micrograph montages of extensive unobstructed areas of normal and abnormal cervices and higher-magnification micrographs of cell components provide improved documentation of the variation in morphology of normal and abnormal epithelia. Use of montages also results in a clear view of ultrastructural changes accompanying the transition from normal to abnormal cervical epithelium.